This invention concerns a fuel injection system for a compression ignition (Diesel) internal combustion engine with an adjustment device, acting on the speed control lever of the fuel injection pump, for increasing the idling speed of the engine when the engine is started in the cold condition.
Inasmuch as the frictional losses are larger when the engine is cold, the idling speed of the engine is substantially lower during cold starting than when the engine is warm. As one means to compensate for reduced idling speed, an adjustment device acting on the speed control lever of the injection pump has been proposed which causes more fuel to be injected during the periods of cold starting and warm-up. Once warm-up has occurred, the adjustment device returns the speed control lever to its normal predetermined idling position, thus avoiding a speed increase of the engine with an attendant smoke development after the cold start.
In addition to increased frictional losses during cold starting and warm-up, there is also a problem of incomplete combustion, since the injection timing of the injection pump is adjusted for normal engine operating temperature. It has been proposed that this problem can be overcome and more complete combustion in the Diesel cycle achieved by advancing the injection timing on cold starting and during the warming-up phase. This can be effected by means of a timing control element acting on an injection timing advancing mechanism.
It is desirable to provide a simple and inexpensive means for improving the engine performance during cold starting and during warm-up, while at the same time permitting normal engine operation after warm-up has taken place.